Preamp with tone controls other then McIntosh C22

Why not just buy an EQ? The adjustments are much more percise and will allow you to make changes in a way that alters the signal the least.

"... to hear SQ difference between two high end pre-amps.  The differences are likely to be subtle."

Only if you don't know what you're doing. If you put together a system where the differences between well made, high end preamps are subtle, you really, really messed up. Its time to rethink your approach to audio.

"Thanx, and yes I can't agree more - need to try it myself, applying major real estate formula: location, location, location - of components in the room I mean.

If you live in the US call The Cable Company. fatwyre.com. They're a Luxman dealer, and I'm sure they can send you a demo unit. But I still say get an EQ instead. Why limit yourself to a very small handfull of choices? The preamp is the single most important piece in your system that you need to get right.

I have a Behringer DEQ 24-96. You can get one for under $300. It has more options on it that you can ever need, and if you run it through your tape loop, you can completely bypass it at will. You can even connect it directly to a dac for better SQ.

"I've been to a lot of audio shows and I never saw an equalizer incorporated in hifi system. Second, it's one more unit on a signal path."

That shouldn't be a factor. You can run the EQ on a different input or through the tape loop. You can insert or eliminate it from the signal path by pressing a button. If you have a local Guitar Center pick one up and do some experimenting. You have 30 days to return it for a full refund.

"Third - EQ Is not a problem with SS preamp, but I do afraid that it can kill the musicality of tubes."

You may have that experiance, but I don't think it will hold true in every case.